Graph Navigational Languages: harnessing the power of structured data on the Web

The Web, traditionally viewed as a vast repository of documents, is being transformed into a huge database by the massive presence of structured data. There are several efforts to publish, describe, organise and interlink structured data on the Web. New research challenges arise in this information space due to the intrinsic decentralised data creation and management, the lack of superimposed schema, the unknown topology of data sources and their links, and the availability of huge volumes of data covering diverse domains. This unbounded and distributed graph of structured data is usually called the Web of Data. The broad objective of this talk is to show the need for formal languages and (automatic) tools to leverage the wealth of structured information available on the Web of Data graph. I will introduce a navigational language, called NautiLOD, which enables the declarative specification of data sources (nodes) on the Web of Data graph as well as the possibility to command actions over data. NautiLOD has a simple syntax and a formal semantics that captures both nodes in the Web graph as well as regions (i.e., subgraphs). NautiLOD has been implemented in the swget tool, which is available for download at http://swget.wordpress.com. I will also briefly mention my other ongoing research activities in the area of graph databases.